Short wave reflector



0a. 22-, 1935. H, LUX 2,018,273

SHORT WAVE REFLECTOR Filed Jan. '7, 1935 INVENTOR HE/l/Z LUX w ww'A1TORNEY Patented Oct. 22, 1935 UNITED QTATE r error:

SHORT WAVE REFLECTOR Germany Application January 7, 1933, Serial No.650,635 In Germany January 13, 1932 3 Claims.

This invention relates to an improved reflector arrangement for shortelectromagnetic waves.

It is known in the prior art that electric waves may be so concentrated.or focussed by the aid of metallic reflectors that the aggregateradiation will be confined to a solid sector. If the reflector has theshape of a paraboloid of rotation or of a parabo-loidal cylinder inwhose focus or focal line the radiator is disposed, and if the laws ofoptical reflection are assumed to hold good, it

can be expected that those radiations as are reflected from the mirroror reflector are orientated parallel. At all points of the solid orspace traversed or filled by the radiations the parallel radiationformed into a beam by the reflector is superposed upon the direct radialradiation issuing from the radiator and upon the dispersion caused bymarginal diffraction. The more perfect the beam formation is, the morewill the parallel radiations, especially at relatively great distance,predominate inasmuch as these decrease at the ratio of (where r=distancefrom the transmitter), while for broadcasting there holds the law Toinsure a thoroughly focussed or absolute beam, also for relativelylittle distances from the transmitter, it is therefore necessary thatthe direct radiation which goes beyond the confines of the sectorconsidered as permissible should be suppressed. In the drawing there areshown diagrammatically two forms of reflectors in which Fig. 1illustrates a reflector with an oppositely mounted screening reflectorand Fig. 2 illustrates 40 a reflector with an oppositely mountedscreening reflector having an aperture. Referring now to Fig. 1 there isshown a means that has been suited to the said end which consists of thedisposition of an oppositely directed reflector. l denotes the meridiansection of a reflector of the form of a paraboloid of rotation, 2 itsfocus, and 3 an oppositely mounted accessory reflector designed tocollect the entire radial radiations. It will be evident that the saidaccessory reflector will screen oil also part of the radiations thathave already been directed parallel; and similarly also such portion ofthe direct radiation as falls within the desired sector is lost.

The present invention has the object of eliminating or at leastlessening these two drawbacks of the screening reflector, in otherWords,

the purpose thereof is to screen as little as possible of the paralleledradiations, and to prevent the wasting of such direct radiations as fallin side the desired sector. For this purpose, the screening reflectorhas a shape according to this 5 invention as shown in Fig. 2. Referringto the latter figure, i denotes again the meridian section of areflector having the form of a cylinder or a paraboloid of rotationwhose focus is located at 2. 3 and 4 are the meridian sections of the 10screening reflector of the invention having the form of the zone of asurface of rotation or of parts of the shell of a cylindrical surface.The aperture 5 between 3 and 4 is chosen so large that the sector whoseapex is located at 2 and which 15 is laterally bounded by the borders of5, is. equal to, or smaller than, the desired or permissible radiationsector. In this manner, not only a larger portion of the directedradiation is utilizable, but also the useful part of the radial 20radiation is utilized. glhe width of the screening reflectors 3 and 4 isso chosen that they are bounded by a line connecting 2 with the ends ofthe mirror 5 (indicated by dotted lines in the drawing Fig. 2) orslightly beyond the same. 2

I claim:

1. A short wave system for reflecting radio waves comprising a reflectorin the form of a parabolic surface of rotation, an accessory refiectorbeing oppositely directed with respect to 30 said first mentionedreflector so as to shut off the undesired part of the direct radiationsof said radio waves, a source of radio waves at the focus of said firstreflector and between said two reflectors, said accessory reflectorhaving an aper- 35 ture and located centrally and in front of the saidfirst reflector so that a useful part of the radial radiation from saidsource is utilized.

2. A short wave system for reflecting radio waves comp-rising areflector in the form of a parabolic surface of rotation, a secondreflector being oppositely directed with respect to said first mentionedreflector and having an aperture centrally located in front of saidfirst reflector, a source of radio waves between said two reflectors,the aperture of said second reflector being so chosen that theunscreened sector having its apex located at the focus of the firstreflector is laterally bound by a border which is equal to the desiredradiation sector.

3. A short wave system for reflecting radio waves comprising a reflectorin the form of a tioned reflector for shutting off the undesired part ofthe direct radiations of said radio waves, a source of radio Waves atthe focus of said first reflector and located between said tworeflectors,

two arcs of a spherical shell whose radius centers at the focus of saidfirst mentioned reflector and is centrally located in front of the saidfirst reflector so that a useful part of the radial radiation isutilized.

HEINZ LUX.

